A 47-year-old male with a medical history of hypertension, and, prior left upper lobe Pancoast tumor status, post video-assisted left upper lobectomy with chest wall and ribs 1-3 resection, presented to the emergency department (ED) with dyspnea, chest heaviness, and near syncope. He was found to be diaphoretic, speaking two- to three-word sentences, tachycardic to 150 bpm, and episodically hypotensive, with oxygen saturations in the 70 percent range on room air.  

Limited point-of-care ultrasound (POCUS) demonstrated a pericardial effusion and a large left-sided pleural effusion. The heart was inferiorly displaced; the apical four-chamber view was obtainable with the probe positioned superior to the umbilicus. Evidence of cardiac tamponade was present, including right ventricular diastolic collapse and greater than 25 percent mitral valve inflow velocity variation (see figure 1). Thoracic surgery requested CT imaging to evaluate for surgical complication; however, the patient was too unstable.  

Figure 1. (A) Mitral valve inflow (MVI) velocity variation measured prior to chest thoracostomy. In this patient, MVI velocity variation is elevated at 37.5 percent, which is indicative of tamponade physiology. (B) Normalized MVI velocity variation after chest tube thoracostomy.

Under ultrasound guidance, a left tube thoracostomy was placed with evacuation of approximately two liters of serosanguinous fluid, resulting in marked improvement and near complete correction of abnormal vitals. A repeat bedside ECG showed complete resolution of tamponade findings (Figure 2), no appreciable pericardial effusion, and relocation of the heart to typical anatomic location.  

Figure 2. (A) Collapsible right heart and signs of tamponade with small pericardial effusion seen at patient presentation and (B) resolution of tamponade findings after chest thoracostomy was performed.

Diagnosis and Management  

Tension physiology is the result of external cardiac compression caused by air, fluid, or a mass when they grow or accumulate rapidly or to a sufficient size to cause localized displacement of structures or changes in pressure dynamics. Compression of the vena cava reduces preload, while compression of the right heart impairs cardiac filling, reducing stroke volume and precipitating obstructive shock.  

In normal physiology, inspiration leads to increased negative intrathoracic pressure, allowing for increased preload of both ventricles. In tamponade, there is increased interventricular dependence, and the septum bows more dramatically into the left ventricle during inspiration, decreasing the amount of blood filling the left heart. This is measured with sonography by placing the pulse wave Doppler gate in the left ventricular space at the opening of the mitral valve leaflets in an apical four chamber view, thereby measuring the speed of left ventricular filling. Mitral valve inflow velocity variability greater than 25 percent is characteristic of cardiac tamponade, as natural interventricular dependence throughout the respiratory cycle is increased and can be thought of as the sonographic equivalent of pulsus paradoxus.¹  

In this case, as the patient had recent thoracic surgery, the presence of both a pericardial effusion and the pleural effusion raised concern about a possible fistula formation. After operative report review, the thoracic surgeon felt this was unlikely. As either or both the pericardial and the pleural effusion could have theoretically been causing the patient’s hemodynamic instability, both a pericardiocentesis and a thoracentesis were considered. Ultimately, the tube thoracostomy was a faster and lower risk procedure and resolved the patient’s tamponade physiology. The pericardial effusion was determined to be physiologic.  

The benefit of using POCUS to establish a diagnosis in a patient with hemodynamic instability or respiratory distress is multifold and has been shown to significantly affect immediate patient care. The bedside lung ultrasound in emergency (BLUE) protocol describes investigation of thoracic and pulmonary pathology using POCUS reliably to  provide an accurate diagnosis within three minutes.² POCUS also enables the provider to re-assess the patient’s hemodynamics, cardiac function, and pulmonary pathology throughout a resuscitation and after specific interventions, such as in this case where the patient is seen to have resolution of his tamponade after chest thoracostomy, avoiding potential further diagnostic uncertainty regarding the etiology of his tamponade physiology, or hemodynamic collapse should he have been laid supine for additional imaging.  

We have described an uncommon case of tamponade physiology caused by the lesser-known tension hydrothorax and not the patient’s associated pericardial effusion. This patient’s POCUS-guided resuscitation was followed by clinical and sonographic resolution of cardiac tamponade after tube thoracostomy. 

Teaching Points: 

• Tension hydrothorax resulting from a pleural effusion is a rare manifestation of tension physiology. 

• Consider extracardiac causes of tamponade in patients without pericardial effusion or small pericardial effusion unlikely to have rapidly developed, and treat the underlying cause of obstructive shock. 

• POCUS allows for efficient, real-time diagnosis of life-threatening conditions in both patients with hemodynamic instability and respiratory distress and allows clinicians to monitor response to resuscitation after intervention. 

Dr. Lynch is an Advanced Emergency Ultrasound Fellow at UPMC, where she recently graduated from emergency medicine residency as a chief resident. 

Dr. Lovallo is an associate professor of emergency medicine at the University of Pittsburgh School of Medicine and Medical Director of the Freedom House 2.0 Program.  

Ms. Bulova is a current third-year medical student at the University of Pittsburgh School of Medicine. 

References 

1. Gelmann D, Slagle D, Seaback J, et al. Advanced critical care ultrasound: use of mitral valve inflow velocity variation in evaluation of cardiac tamponade. https://www.emra.org/emresident/article/CCUS-mv-variation. Published June 12, 2024. Accessed December 6, 2024.
2. Lichtenstein DA, Mezière GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol [correction appears in Chest. 2013;144(2):721]. Chest. 2008;134(1):117-125.